Research Article Study of Coating Geometries and Photoluminescence Properties of Metal Nanoparticles/Graphite Composites Pasquale Barone, Marianna Barberio, Fabio Stranges, and Fang Xu Biology, Ecology and Earth Science Department and Physics Department, University of Calabria, 87036 Rende, Italy Correspondence should be addressed to Marianna Barberio; marianna.barberio@fs.unical.it Received 30 December 2013; Accepted 30 March 2014; Published 17 April 2014 Academic Editor: Demeter Tzeli Copyright © 2014 Pasquale Barone et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In this work we present the results of a study of growth and characterization of metal nanoparticles (Ag, Au, and Co)/carbon surfaces. Te nanoparticles grew by laser ablation technique and their dimensions were controlled by light scattering study and AFM microscopy before their insertion on graphite surface. Nanoparticles appear randomly disposed on carbon surfaces aggregating to form big particles only in the case of silver. Te diferent behavior of metal nanoparticles on carbon surface was explained in terms of diferent metal wetting of surface, in agreement with previous theoretical results of He et al. Chemical information, obtained by X-ray photoelectron spectroscopy, indicated that the doping process is a simple physisorption while the interfacial interaction between particles and carbon layers causes local defects in graphite structure and the appearance of a strong photoluminescence signal for all composites. Moreover, the visible optical absorption decreases about 10% indicating the progressive metallization of carbon surface. 1. Introduction Carbon nanotubes (CNT) and graphene have attracted con- siderable interest in scientifc community for their use in the fabrication of nanoelectronics devices as feld efect tran- sistors or nanodiodes. In these frameworks the interaction between metals and carbon based substrates at nanometric scale is of critical importance in determining device char- acteristics [1]. In fact, unlike silicon devices, the electrodes on carbon structures are made up of metals and so the control of contact resistance (including coating geometries and interfacial interactions) is strategic [1]. Te study of interfacial properties and coatings geometry between diferent carbon surfaces and metals is so funda- mental [1]. Various experiments have been carried out to investigate the contact between diferent metals and carbon structures [1–3]. As example the metal coating geometries on CNT are closely related to the contact resistance [1]. Coating of metals such as Ti, Pd, and Ni lead to the formation of continuous or quasicontinuous layers on the CNT indicating frm adsorption and low contact resistance, while metals such as Fe, Al, and Au lead to the construction of isolated clusters indicating weak interaction and large contact resistance [1, 4–7]. Studies based on density functional theory attribute the metallic coating properties to the metal-carbon binding energy [6, 7], while study on traditional nucleation and wetting theories indicate in the diferent metal wetting of carbon surfaces the diferent coating geometries [1]. Moreover, the combination between a carbon nanostruc- ture and metal nanoparticles is much interesting because metal nanoparticles exhibit very important properties that can be improved by the mix with carbon based nanomaterials [1, 8–17]. In our previous work [18], we demonstrate that metal nanoparticles (growth by laser ablation techniques and aferwards inserted in carbon nanotubes networks) are distributed on carbon surface to forming coatings geometries that are uniquely related to wetting between carbon and metals. We do not observe formation of chemical bonds between tubes and nanoparticles but the introduction of several local defects on CNT structures which causes strong changes in morphology and the appearance of a strong photoluminescence signal in visible region [18]. Here we extend the study of interaction between metal nanoparticles (both noble and transitions metals—Au, Ag, Hindawi Publishing Corporation Journal of Chemistry Volume 2014, Article ID 204028, 6 pages http://dx.doi.org/10.1155/2014/204028